Natural Climate Variation Outweighs Some Global Warming Effects

March 4, 1999

A new projection of climate conditions in Europe for 2050 indicates that natural shifts in climate can make it nearly impossible in some cases to tell whether warming from greenhouse gases is having any clear effect, reports Science News.

British researchers led by Mike Hulme of the University of East Anglia compared the effects of human-caused climate change on wheat yields and the amount of water in rivers -- as predicted by computer modeling -- with natural variations that always occur.

Their study, published in the February 25, 1999, issue of Nature:

Suggests human-caused climate change will noticeably increase river runoff in northern Europe and decrease it in southern Europe.

But in central and western Europe, the predicted changes will not exceed the range of natural fluctuations.

They also found the model predicted wheat yields in Finland, Germany and the Netherlands will increase by significant amounts, while in other countries it will not be above natural variation.

However, when they factored in the fertilizing effect of additional carbon dioxide in the air, they found wheat yields increased in all countries, by 9 percent to 39 percent.

The new study fits into a growing awareness that climate can undergo decades- long natural swings, with occasionally harmful consequences.

"There's an awful lot we should be doing to adapt to current climate variability," says Hulme, "and if we properly adapt to that full range of natural variability, then we'll actually be in a better position later on in the next century to withstand anything that human-induced climate change will throw at us."